A337502 - OEIS

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A337502

Minimum number of painted cells in an n X n grid to avoid unpainted tetrominoes.

%I #13 Aug 30 2020 18:02:36

%S 0,1,3,6,9,15,20,27,34,43

%N Minimum number of painted cells in an n X n grid to avoid unpainted tetrominoes.

%e For n = 4, painting only 5 cells would leave an unpainted tetromino, but painting the following 6 cells avoids all unpainted tetrominoes:

%e . . X .

%e X X . X

%e . . X .

%e . X . .

%Y Cf. A337501.

%K nonn,more

%O 1,3

%A _Rob Pratt_, Aug 29 2020